You are disabling netbios name resolution when
you set the following:
name resolve order = host
Sine you are in domain mode security, Samba must resolve the
DOMAIN<0x1b> and DOMAIN<0x1c> names.
Set this to
name resolve order = host wins bcast

ok, changing name resolve order, but it's odd that I was getting away
with using
name resolve order = host
at all. I fixed the link to my logs - which shows it working for a long
while before dying mysteriously.

Created attachment 348[details]
log files from error period
this file contains my samba-3.0.0 log directory (with log level = 10) during a
period where users were seeing "NT_STATUS_NO_LOGON_SERVERS"
the log files have been pruned to save space - I discard any that didn't have
these errors.

changed config file to read:
name resolve order = host wins bcast
and still spuriously get NT_STATUS_NO_LOGON_SERVER.. note, this machine is
but one of many samba servers contacting gate3, none of the others experience
this problem (or if they did, I dropped them back to security=server).
I just attached relevant log files, with log level = 10.

Rick,
It is possible that the other 2 samba boxes (with security =
server) are draining the sockets on your Samba pdc since each smbd
on the file server will maintain a connection to the DC.
Unless you have some other idea why nmbd is not responding
on port 137? Maybe check the output from netstat on the
Samba PDC?

the other 2 gate machines are using an smbpasswd file, which is dumped
out of the MIT database periodically.
gate3 (which does domain authentication) is also being used by a few other
samba servers around campus, but none of them ever see this transient problem.